1. Field of the Invention
The present invention relates to an X-ray tomography apparatus with a slip ring.
2. Description of the Related Art
In an X-ray computed tomography (CT) apparatus of the continuous-rotation type, an X-ray tube and X-ray detector are arranged opposite each other on a rotating frame, whereby the rotating frame is rotated. Electrical power supply and/or electrical signal transfer is needed between the rotating and stationary sides of the rotating frame. Normally, this electrical power supply and/or electrical signal transfer is performed through a slip ring which is attached to the rotating frame on the rotating side and a brush on the stationary side. The slip ring is rotated as the rotating frame is rotated, and is continuously brought into contact with the brush fixed on the stationary side. Therefore, wear debris is generated from friction portions of the slip ring and brush. If the wear debris scatters in the X-ray CT apparatus, it may adversely affect electronic components and the like mounted in the apparatus. If the wear debris enters a support bearing that supports the rotating frame, for example, it causes mechanical wear and shortens the life of the bearing. If the wear debris adheres to circuits of precision electronic devices, such as the X-ray tube, X-ray detector, etc., it may break electrical insulation and cause malfunctioning of the devices.
In this background, JP-A H06-5340 (KOKAI) discloses an X-ray CT apparatus in which wear debris is prevented from scattering anywhere from a slip ring by a labyrinth seal or dust seal that is installed near the slip ring.
However, recent X-ray CT apparatuses are improved so that a rotating frame with an X-ray tube and X-ray detector is rotated at high speed to obtain higher-definition images. Since the slip ring, as well as the rotating frame, is rotated at high speed, friction speeds of the slip ring and brush increase, so that the production of wear debris tends to increase. In an X-ray CT apparatus furnished with a non-contact seal, such as a labyrinth seal or shield plate, there is a gap between a rotating frame and stationary-side frame such that the wear debris leaks through it. Therefore, the wear debris cannot be prevented from scattering in the apparatus.
Thus, according to the conventional X-ray CT apparatus with the slip ring, the labyrinth seal cannot fully prevent scattering of wear debris, so that it is difficult to prevent the wear debris from scattering in the apparatus in which the electronic devices and the like are installed. In consequence, the X-ray CT apparatus preferably securely prevent wear debris from scattering in it.